Interleukin-6 and its considerable role in the pathogenesis of thyrotoxicosis-related disturbances of bone turnover in postmenopausal women.

BACKGROUND Thyrotoxicosis is more frequent in postmenopausal women than in the general population, effectively accelerating bone turnover. Interleukin-6 has been shown to be involved in the pathogenesis of bone disorders. Thus, the aim of the present study was to assess the role of IL-6 and its soluble receptor in the pathogenesis of thyrotoxicosis-related disturbances of bone turnover in oestrogen-deficient women. MATERIAL AND METHODS The study was carried out in 40 subjects with toxic nodular goitre in three groups: Group 1 - 13 premenopausal females, mean age 36 ± 15 years (PremTx→PremEu); Group 2 - 12 postmenopausal females, mean age 66 ± 14 years (PostTx→PostEu); and Group 3 - 15 males, mean age 45 ± 21 years (MTx→MEu). Overt thyrotoxicosis and euthyreosis after treatment with thyrostatics were confirmed by thyrotropin, free thyroxine and free triiodothyronin concentrations. Serum levels of bone turnover markers: TRACP5b and osteocalcin as well as serum IL-6 and IL-6sR were determined using ELISA kits. RESULTS TRACP5b/osteocalcin quotient was significantly elevated in the PostTx females compared to the PremTx women (p < 0.02). There was a positive correlation between serum TRACP5b and osteocalcin in the studied patients (R = 0.45, p < 0.001). Levels of serum IL-6 values were significantly elevated in PostTx: 3.0 (2.14-6.40) and MTx: 2.24 (1.60-5.10), compared to PremTx females: 1.39 (0.96-2.14) (p < 0.01 and p < 0.05 respectively). There were significant positive correlations between IL-6 and IL-6sR concentrations (R = 0.22, p < 0.05) and between IL-6sR and TRACP5b serum levels (R = 0.23, p < 0.05). CONCLUSIONS The results of our study suggest that interleukin-6 plays a considerable role in the pathogenesis of thyrotoxicosis-related disturbances of bone turnover in oestrogen-deficient women.